Heterogeneous catalyst process

ABSTRACT

A process using heterogeneous resin-bonded aluminum phenoxide catalyst to alkylate phenols, the catalyst per se, and a process for making the catalyst. The inventive alkylation process uses ortho-tert-butylphenoxide bonded to a phenolformaldehyde condensation resin heterogeneous catalyst to prepare 2,6-di-tert-butylphenol from isobutylene and ortho-tert-butylphenol.

This application is a division of application Ser. No. 748,733, filedJune 25, 1985 and now U.S. Pat. No. 4,631,349. This application isrelated to applications Ser. No. 748,744 filed June 25, 1985 and nowU.S. Pat. No. 4,628,127, and Ser. No. 899,904 filed Aug. 25, 1986.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to heterogeneous catalysts and processes usingsuch catalysts for the alkylation of phenols. More particularly, thisinvention relates to the preparation of ortho-alkylphenols in highpurity with a minimum of impurity by-products.

2. Description of the Prior Art

The alkylation of phenols has been carried out using homogeneousaluminum phenoxide catalysts in a pressurized liquid/gas reaction toprepare ortho-alkylphenols. However, such processes commonly producesignificant amounts of 2,4-dialkylphenols or 2,4,6-trialkylphenols andsuffer from other problems. In particular, current homogeneouslycatalyzed alkylations have waste problems and require acidification andneutralization steps which increase the overall cost of the process.

U.S. Pat. No. 3,355,504 describes the "ortho catalyst" used for theconversion of an ortho-alkylphenol to a 2,6-dialkylphenol. The orthocatalyst is an aluminum 2-substituted phenoxide which strongly directsthe production of 2,6-dialkylphenols rather than the2,4,6-trialkylphenol. The "ortho catalyst" must be used in thesubstantial absence of phenol which does not have ortho substituents andethers such as phenyl butylether which may generate phenol. This isbecause the phenol tends to replace the ortho-substituted phenol moietyon the aluminum 2-substituted phenoxide catalyst thereby destroying thestrong alkylation directing effects.

The process described in U.S. Pat. No. 3,355,504 and other relatedprocesses use a homogeneous aluminum phenoxide catalyst which, afteralkylation with, e.g., isobutylene, must be acidified for a phase cutfollowed by neutralization with sodium carbonate so as to avoidcorrosion of distillation columns and also avoid dealkylation of productin the columns which are operated at temperatures that might otherwisefavor dealkylation. Thereafter, the aqueous phase of the mixture is sentto a caustic solution for precipitation of an aluminum salt which iscontaminated with phenol. This presents an immense disposal problemsince the aluminum cannot otherwise be used or recovered. In the past,this aluminum precipitate has been disposed of as a phenol-bearing wastestream.

U.S. Pat. No. 3,652,685 describes the separation of aluminum catalystmaterials which generate phenol-bearing aluminum waste.

SUMMARY OF THE INVENTION

The process of the present invention overcomes the disadvantagesassociated with separation procedures and greatly diminishes the costsof disposing of such waste. The invention is directed to an economicalprocess for alkylating phenols, a new catalyst for the process, and amethod of preparing the catalyst.

The present invention is a process for alkylating phenols comprisingreacting a mixture of:

(a) a phenol having at least one ortho or para position unsubstitutedexcept for H;

(b) an olefin; and

(c) a heterogeneous catalyst comprising an aluminum phenoxide bonded toa solid polymeric resin.

The present invention is also a process for preparing a resinouscatalyst useful in the alkylation of phenols, said process comprisingreacting or an aluminum compound with a solid polymeric resin to attachaluminum to said resin and thereafter reacting a phenol with thealuminum attached to said resin to form a resin-bonded aluminumphenoxide catalyst.

The present invention is also a resin-bonded aluminum phenoxide catalystof the formula:

    (Resin).sub.x --Al(O--C.sub.6 R.sub.5).sub.y

wherein

x is 1 or 2;

y is 1, 2, or 3;

x+y is 3 or 4;

C₆ R₅ is aromatic wherein the R are independently selected from H, alkylof from 1 to 12 carbon atoms, cycloalkyl of from 5-12 carbon atoms, andaralkyl of from 7-12 carbon atoms, and

the Resin is the residue from a solid polymeric resin.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the invention is a process for alkylatingphenols comprising reacting a mixture of (a) a phenol having at leastone ortho or para position unsubstituted except for H; (b) an olefin;and (c) a heterogeneous catalyst comprising an aluminum phenoxide bondedto a solid polymeric resin.

The process is applicable to a broad range of phenols. The terms "aphenol" and "phenols" are used in a generic sense to include allaromatic hydroxy compounds having at least one hydroxy group bonded toan aromatic ring. The phenols usable with the process are those havingat least one ortho or para position open for substitution. These includethe compound phenol (C₆ H₅ OH), ortho-cresol, para-cresol,2,6-dimethylphenol, paraethylphenol, 4-phenylphenol, alpha-naphthol,β-naphthol, ortho-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol,2,4-dibromophenol, 4-bromophenol, hydroquinone, 4-methoxyphenol,ortho-ethoxyphenol, ortho-tert-butylphenol, ortho-sec-butylphenol,ortho-isopropylphenol, 2,4-di-tert-butylphenol, 2,4-di-sec-butylphenol,2,6-di-sec-butylphenol, 2,6-di-tert-butylphenol, 2,4-di-tert-amylphenol,ortho-amylphenol, 2-n-octylphenol, 2-(4'-dodecyl)phenol,2-(2'-decyl)phenol, 2-tert-amylphenol, 2,4-di-n-octylphenol,2,6-diethylphenol, 2,6-dibenzylphenol, ortho-benzylphenol,2,4-dibenzylphenol, 2(3'-nonyl)phenol, 2(3'-undecyl)phenol,2-n-hexylphenol, 2,6-di-n-hexylphenol, 2-cyclohexylphenol,4-cyclopentylphenol, 2,6-dicyclopentylphenol, 2,6-diisopropylphenol,ortho-isopropylphenol, 2,4-diisopropylphenol, ortho-n-butylphenol,2-n-butyl-6-cyclohexylphenol, 2-pentyl-4-tert-butylphenol,2(2'-heptyl)phenol, ortho-phenylphenol, 2,4-diphenylphenol,2-ethyl-4-benzylphenol, and the like. The phenols may optionally bemeta-substituted.

The phenolic reactants of the invention may have an optional halosubstituent. The halo may be, e.g. bromo or chloro.

A preferred class of phenols includes the compound phenol and variouslower alkyl substituted phenols having at least one ortho positionunsubstituted except for hydrogen such as ortho-tert-butylphenol,ortho-isopropylphenol, 2,4-di-tert-butylphenol, ortho-cresol,para-cresol, ortho-sec-butylphenol, and the like. Very highly preferredphenols usable with the invention are the compound phenol,ortho-tert-butylphenol, ortho-isopropylphenol, andortho-sec-butylphenol.

The resin-bonded aluminum phenoxide heterogeneous catalyst of theinvention is a stable aluminum complex. The complex is tricoordinatedbut is in some cases tetra-coordinated. The degree of coordinationdepends on the resin used and especially on the phenoxide moiety of thecatalyst. An unsubstituted phenoxide moiety tends to tetracoordinatemore than a substituted phenoxide moiety.

The process of the invention is applicable to phenols having thestructure: ##STR1## wherein R₁, R₂, and R₃ are independently selectedfrom the group consisting of H, alkyl of from 1-12 carbon atoms,cycloalkyl of from 5-12 carbon atoms, and aralkyl of from 7-12 carbonatoms wherein at least one of R₁, R₂, and R₃ is H. In a preferredembodiment at least one of R₁ and R₂ is hydrogen. In a more preferredembodiment of the invention, R₂ and R₃ are both H and R₁ is alkyl offrom 1-12 carbon atoms, more preferably sec-alkyl or tert-alkyl, stillmore preferably sec-butyl, isobutyl, or tert-butyl. Alternatively, R₁may be methyl in still another embodiment of the invention. The phenolsmay optionally be meta-substituted.

In general, the heterogeneously catalyzed process of the presentinvention is usable with any of the various phenols which wereheretofore catalyzed by homogeneous catalyst systems.

A process of the invention is preferably carried out in a liquidreaction medium. The medium may be an excess of one or both of thereactants or an innocuous liquid medium.

For alkylation processes using a heterogeneous "ortho" catalyst, the useof excess olefin (e.g., isobutylene) is highly preferred because thispermits carrying out the process at a temperature below the meltingpoint of the product 2,6-dialkylphenol. As the product is formed, itremains, however, dissolved in the excess olefin. Operation at the lowertemperature advantageously decreases the amount of by-products andincreases the yield based on ortho-alkylphenol.

In one embodiment, the liquid reaction medium is a hydrocarbon. Thus anyof the well known hydrocarbon reaction mediums such as toluene, hexane,heptane, trimethylpentane, xylene, and the like are suitable for theinvention, toluene being preferred.

In general, the olefins used in homogeneously catalyzed alkylationprocesses are also usable in the heterogeneously catalyzed alkylationprocess of the invention. The term "olefin" is meant to includemonoolefinic alicyclic alkenes of from 2-12 carbon atoms, cycloalkenesof from 5-12 carbon atoms, and aralkenes of from 8-12 carbon atoms. Thatis, the olefins of the process of the invention are generallyunsaturated compounds of the aliphatic, alicyclic, or araliphatic serieswith olefinic double bonds. Typical representatives of such compoundsare those containing ethylenic unsaturation, such as ethylene,propylene, butylene, pentene, hexene, cyclopentene, cyclohexene,cyclooctene, styrene and α-methylstyrene including all possible isomers.It is particularly advantageous to use lower olefins such as thoseavailable from catalytic cracking processes, e.g. ethylene, propylene,amylene, and the isomeric butenes, such as 1- or 2-butene. In additionto the ethylenic unsaturated type compounds such as pent-1-ene,n-hex-1-ene, n-oct-1-ene, and the like, such alkenes substituted bymethyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, ortert-butyl in the 2-, 3-, or 4-position are also usable. These include2,3-dimethyl-n-butene, 3,3-dimethyl-n-butene, 2,5-dimethylheptene,3,3-dimethylheptene, 2,3,4-trimethylheptene, 2,4-dimethylheptene,2,3-dimethylheptene, 4,4-dimethylheptene, 2,3-diethylhexene,2-methyl-3-ethylpentene, 2,4,4-trimethylpentene,2,3,3,4-tetramethylpentene, and analagous alkenes wherein the doublebond is in the 2-position or 3-position of the molecule. Also usable arethe branched alkenes as obtained in the form of mixtures from thedimerization of isobutene or n-butene or the trimerizing of isobutene orn-butene or propene or by tetramerizing propene. Arylalkenes can be usedsuch as styrene, alpha-methylstyrene, ortho-methylstyrenemeta-methylstyrene, para-methylstyrene, 3,4-dimethylstyrene,ortho-ethylstyrene, 3,4-diethylstyrene, ortho-propylstyrene,ortho-isobutylstyrene, ortho-tert-butylstyrene, and the like.

The catalyst materials of the invention are referred to as heterogeneousbecause they are solid in nature and do not usually dissolve in theotherwise homogeneous reaction mixture of a phenol and olefin (andliquid reaction medium such as toluene). Compare the homogeneouslycatalyzed processes wherein aluminum phenoxides are formed by thereaction of aluminum or aluminum alkyls with a phenol to form a catalystwhich is generally readily dissolved in the reaction medium.

Therefore, in a batch operation it is generally preferred in the processof the invention to use agitation, preferably high speed sheer agitationto assure the distribution of the heterogeneous catalyst solid materialsthroughout the reaction mixture. Excess agitation which would destroythe structure or particle size of the heterogeneous catalyst is usuallynot helpful and is undesirable. Generally, any of the aluminumprecursors and a phenol which was used to prepare a homogeneous catalystheretofore used are also usable according to the present invention toprepare a heterogeneous catalyst for the process of the invention.

In most embodiments of the invention, it is generally preferred that theolefins and alkyl groups have at least 4 carbon atoms as the process isthereby accomplished more speedily. It is particularly preferred thatisobutylene be used and that the mono-ortho-substituted phenol be2-tert-butylphenol. The products achieved by using these materials arecommercial antioxidants which have a strong demand in the market place.In general, in a preferred embodiment of the invention, the olefincorresponds to the alkyl substituent R₁ as given in structure I abovethereby providing a more facile and speedier reaction. Thus theheterogeneous "ortho catalyst" is a particularly preferred embodiment ofthis invention.

The phenols usable to prepare the heterogeneous catalyst of theinvention include any of the phenols mentioned above as reactant and,for purposes of preparing a heterogeneous "ortho catalyst", the orthosubstituted phenols are preferred. Of course, the compound phenol, C₆ H₅OH, usable as a reactant above, is also usable to prepare aheterogeneous catalyst of the invention wherein aluminum phenoxide isbonded through aluminum to a solid polymeric resin useful in thealkylation of phenols. In a highly preferred embodiment using theheterogeneous "ortho catalyst", the ortho alkyl substituent of theortho-alkylphenol to be alkylated is the same as the alkyl substituenton the aluminum phenoxide portion of the heterogeneous ortho catalyst.

The quantity of catalyst to be used in the invention depends on theactivity of the particular catalyst chosen, the nature of the underlyingresin, and the particular alkylation procedure to be carried out. Ingeneral, a discontinuous/batch alkylation can suitable be carried outwith as little as 0.1% by weight to as high as 30% by weight catalystbased on the weight of phenol to be alkylated. More preferably, a rangeof 0.5 to 10.0% by weight catalyst based on the weight of phenol isconveniently used. In a continuous (e.g. fixed bed) method of operation,a high quantity of catalyst may be desired wherein the catalyst weightrange is from 0.02 to 10 parts by weight catalyst per part by weight ofphenol per hour passed therethrough. More preferably, the range is about0.4 to 1.0 parts by weight catalyst per 1.0 part by weight of phenol perhour passed through the catalyst.

The heterogeneous catalysts of the invention include the reactionproducts formed by first reacting an aluminum alkyl or other reactivealuminum compound with a solid polymeric resin to bond the aluminum tothe resin followed by reaction with a phenol to form an aluminumphenoxide bonded to the solid polymeric resin. The reactive aluminumcompounds usable for preparation of the heterogeneous aluminum phenoxidecatalyst include aluminum phenoxides, aluminum halides, aluminum alkyls,and others. Aluminum alkyl compounds such as trimethylaluminum,triethylaluminum, tri-n-propyl-aluminum, diisobutylaluminum hydride, andtriisobutylaluminum may be used. Also suitable are compounds such asdiethylaluminum malonate, diethylaluminum hydride, diethylaluminumchloride, ethylaluminum dichloride, ethylaluminum sesquichloride,methylaluminum sesquichloride, alane, triphenylaluminum, and the like.Other aluminum source compounds are also usable to react with a resinthereby bonding the aluminum to the resin. For example, diphenoxyaluminum hydroxide is usable.

The aluminum compounds can be added directly to the reaction systemcontaining the resin or may be added along with an inert solvent such ashexane, benzene, or toluene. The preferred aluminum alkyl for bondingaluminum to a solid polymeric resin, because of its high reactivity, istriethylaluminum.

The solid polymeric resins of the heterogeneous catalysts of theinvention may be of the ion exchange type, the adsorber type, or anothertype. In the process of preparing the heterogeneous catalysts of theinvention the resins are chemically reacted with aluminum compounds.

The solid polymeric resins usable in the heterogeneous catalysts of theinvention in general include all resins which have functional groupswith a highly electronegative atom with a donateable hydrogen atom orother leaving group which facilitates reaction of the resin with analuminum compound (aluminum phenylate, aluminum alkyl, aluminumphenoxide, etc.). The resin usable for the heterogeneous catalyst of theinvention include those with amine, thiol, carboxylic acid, sulfonicacid, hydroxy, phenol, and other functionalities as well as hybridresins with mixed functional groups. Furthermore, the resins may bematrix-modified by chlorination, nitration, amination, alkylation, orother modification of the resin matrix.

The various solid polymeric ion exchange, adsorbant, and other resins ofthe invention may be described in many fashions and are well known inother arts for their adsorption and ion exchange capabilities.

Solid polymeric resins usable with the invention includephenol-formaldehyde condensation resins having a hydroxyl functionalgroup such as Rohm & Haas Duolite® S-761 resin support; phenolic/amineresins having hydroxyl and amine functional groups such as Rohm & HassDuolite® S-587 support; mixed amine resins having amino, dialkylamine,etc. functional groups such as Rohm & Haas Duolite® A-7 support;sulfonic acid resins having SO₃ H functional groups such as Rohm & HaasAmberlyst® 15 resin or Dow Chemical Company Dowex® MSC-1 resin; acrylicester resins having the functional group--RCOOR--such as Rohm & HaasXAD-7 resin or Rohm & Haas XAD-8 resin; sulfoxide resins having thefunctional group--RCOORSOR--such as Rohm & Haas XAD-9 resin; amide ionexchange resins having the functional group--RCONHR--such as Rohm & HaasXAD-11 resin; phenolic/carboxlic resins having hydroxyl and carboxylic(COOH) functional groups such as Rohm & Haas Duolite® CS-100 resin;thiol resins having the functional group --SH such as Sybron CorporationAG-52-88B resin; or carboxylic acid resins having the functional group--COOH such as Dow Chemical Company Dowex® NWC-1 resin.

The cross-linked phenol-formaldehyde condensation resin of a preferredembodiment of the invention is in the form of moist granules having aparticle size of about 0.3 to 1.2 mm with a moisture retention capacityof about 51-56%. Preferably, the resin is dried under vacuum at about80° C. until substantially all the absorbed water which it normallyretains has been removed. This particular resin is not always stableabove 80° C. The resin has a typical surface area of about 200-300square meters per gram and a pore volume of about 0.45 to 0.55 cubiccentimeters per gram. The specific gravity of the resin is 1.11.

A generalized structure of a typical unit of Rohm & Haas Amberlite XAD-8is given below: ##STR2##

The Rohm & Haas Amberlite XAD-9 resin has the following substantialrecurring structure: ##STR3##

The use of the above described resins to form a heterogeneous catalystfor alkylation of phenols is highly desirable so as to provide an easilyseparable catalyst from the liquid reaction mixture containing alkylatedproduct thereby avoiding the expensive hydrolysis procedure used withhomogeneous catalyst systems. Thus, aluminum phenoxides including the"ortho catalyst" type of aluminum phenoxide can be chemically bonded tosolid polymeric resins and used as a heterogeneous catalyst in thereaction of phenols and olefins. The catalyst life and the rate ofaluminum loss varies depending upon the particular resin and thereaction conditions.

The yields for the processes using the heterogeneous catalysts of theinvention are very similar to those observed for the homogeneous routebut the process is, overall, much more economical. The heterogeneousreactions are sometimes slightly lower than the rates for homogeneousreactions with equivalent amounts of aluminum. However, this does notseriously detract from the significant savings available by the decreasein phenol-contaminated aluminum waste.

The present heterogeneously catalyzed process of the invention providesas much as a ten-fold decrease in the amount of aluminum waste streamand greatly reduces the distillation and energy requirements byimproving conversions per pass. The phenol-formaldehyde condensationresin and cross-linked acrylic polyester resins are preferred for someembodiments of the invention including the heterogeneous "orthocatalyst".

In each homogeneously catalyzed alkylation of a phenol the amount ofaluminum used as catalyst and lost is about 0.48 weight percent of thetotal reaction mixture or about 0.71 weight percent of the2,6-dialkylphenol product. In experiments using the heterogeneouscatalysts of the invention, as much as about 0.45 weight percent of thealuminum may be lost in a first heterogeneously catalyzed alkylation,but the rate of loss drops off precipitously (to nil) in subsequentalkylations recycling the same aluminum/resin heterogeneous catalystwhile the catalyst remains active.

In a preferred embodiment of the present invention, an ortho-alkylphenolis first prepared by the olefin (e.g. isobutene, butene-1, etc.)alkylation of phenol using an aluminum-containing catalyst such as gammaalumina. Thereafter excess phenol or phenol generating ethers such asphenyl tert-butylether are removed from the ortho-alkylphenol(preferably ortho-tert-butylphenol) to obtain a substantially pureortho-alkylphenol which is subsequently alkylated in a heterogeneouscatalyst system using e.g. a phenol formaldehyde resin such as Duolite®S-761 ion exchange resin. The absence of phenol and phenol-generatingethers is well recognized as a requirement for the homogeneous orthocatalyst and is equally applicable here for the heterogeneous orthocatalyst since the compound phenol C₆ H₅ OH tends to replace the orthocatalyst material and thereby decrease the ortho influencing effect ofthe ortho catalyst material resulting in an increase ofpara-substitution products.

Advantageously, the process of the invention may be carried out whereinthe heterogeneous catalyst of the invention is positioned in a fixed bedof sufficient size to provide conversion of the ortho alkylphenol(preferably ortho-tert-butylphenol or ortho-sec-butylphenol) reactant to2,6-dialkylphenol with a very low production of 2,4,6-trialkylphenol and2,4-dialkylphenol. Preferably, the same olefin is used in both stages ofthe preparation of the 2,6-dialkylphenol. For example, a preferredembodiment is the mono-ortho-alkylation of phenol with a gamma aluminacatalyst using isobutylene followed by distillation to remove anyremaining phenol and phenol-generating ethers in turn followed by thealkylation of the ortho-tert-butylphenol with isobutylene in thepresence of the heterogeneous resin-bonded aluminum phenoxide catalystwherein the phenoxide portion of the catalyst isortho-tert-butylphenoxide.

According to the invention a reactive aluminum compound as previouslydescribed is reacted with a solid polymeric resin to attach or bondaluminum to the resin. For example, triethylaluminum may be added to aphenol-formaldehyde condensation resin thereby attaching the aluminum tothe oxygen of the phenolic group which is pendant on the resin. Thisevolves ethane for each hydrogen removed from the pendant phenolic groupof the resin. Alternatively, the triethylaluminum may bond with twoadjacent pendant phenolic groups of the resin to evolve two moles ofethane, one for each hydrogen atom extracted from the hydroxyl of thependant phenol groups. This leaves the aluminum twice bonded to theresin with one remaining pendant reactive ethyl substituent on thealuminum.

Typically, excess triethylaluminum or similar aluminum alkyl is removedby full toluene wash. In the next step of catalyst preparation, a phenolof choice is reacted with the aluminum which has been singly or doublybonded to the resin so as to replace one or both, usually both of thependant ethyl (more generally alkyl) groups still attached to thealuminum. Where only one or two pendant ethyl groups remains on thealuminum which has been twice bonded to the resin, then only one or twoadditional moles of ethane are evolved when the phenol of choice isreacted with the aluminum. The above procedure provides a heterogeneouscatalyst species having one, two, or three (where tetracoordinationprevails) phenoxide groups attached to aluminum which is in turn bondedonce or twice to the resin structure.

In other cases such as where the resin is a cross-linked polyesterresin, an aluminum moiety such as triethylaluminum attacks the pendantester group to react with the carboxylic substituent in such a fashionthat one of the ethyl groups of the triethylaluminum attaches to thecarbon of the pendant carboxylic group and the remaining diethylaluminumresidue attaches to the carbonyl oxygen of the carboxylic ester. Thus,it is observed that no ethane is in fact evolved upon addition oftriethylaluminum to cross-linked polyester resin. Following addition ofthe triethylaluminum or similar aluminum compound to the polyesterresin, the phenol of choice such as ortho-tert-butylphenol is added toreplace both ethyl groups pendant on the aluminum which has beenattached to the pendant polyester group of the resin. This provides aheterogeneous catalyst having an ethyl group attached to the carbon ofthe pendent ester and an aluminum diphenoxide (or triphenoxide withtetracoordination) attached to the formerly double bond oxygen of theester thereby providing an effective heterogeneous resin-bonded aluminumphenoxide catalyst.

In the preparation of the heterogeneous catalyst of the invention, asolid polymeric resin having functional groups which have a highlyelectronegative atom with a donateable hydrogen atom or otherelectropositive leaving group (to facilitate reaction with the aluminumcompound) is reacted with an aluminum compound to substituted thealuminum on the resin for the donated hydrogen atom or other leavinggroup. The portion of the resin remaining after such a reaction isreferred to as the residue of the resin and represented as "Resin-".Thus for the phenolformaldehyde condensation resin having pendanthydroxyl groups, "Resin-" is the polymeric structure with the oxygen ofthe pendant hydroxyl group bonded to the aluminum. Similarly, thependant ester group --COOR of the cross-linked polyester resins, whenreacted with triethylaluminum, becomes ##STR4##

In accordance with the above, the invention also includes a resin-bondedaluminum phenoxide catalyst as described above. A preferred embodimentof the inventive catalyst is one wherein the resin is aphenol-formaldehyde condensation resin.

The heterogeneous catalyst of the invention provides a new route toortho-alkylphenols, especially commercially valuable phenols such as2,6-di-tert-butylphenol, ortho-sec-butylphenol, and the like.Furthermore, the heterogeneous catalyst process of the invention is wellsuited to a fixed bed embodiment for a continuous process when the bedis properly sized to provide the reactivity required by the reactionconditions, the phenol being alkylated, and the olefin being used. Useof the heterogeneous catalyst of the invention reduces pollution controlproblems by greatly reducing the amount of phenol-bearing aluminum wasteencountered in homogeneous aluminum aryloxide catalyst systems therebygreatly reducing the operating costs for alkylating phenols. Use of theheterogeneous catalyst systems of the invention has resulted in veryhigh yields suitable for commercial operation. For example,ortho-tert-butylphenol and isobutylene may be reacted to form2,6-di-tert-butylphenol in a yield as high as 98.5%.

The heterogeneous catalysts of the invention are suitable forregeneration after use by simple toluene washing and retreating withaluminum alkyls or the like. In some embodiments it may be preferable toreduce the rate of agitation of the reaction wherein agitation is usedto disperse the heterogeneous catalyst. Too high a rate of agitation mayresult in breakdown of the resin particles and/or destruction of thecatalytic activity.

In alkylations performed using various resins, the thiol resin was foundto be catalytically very active on the first run but somewhat slow insubsequent runs. The ester resin was found to have a great aluminumcapacity and showed good catalytic activity for up to 5 cycles. Thephenolic resin was found to have good aluminum retention capability butthe catalyst life may be short in some cases.

In preparation of a heterogeneous ortho catalyst the catalyst was easilypoisoned by phenol, water, and the like. Furthermore, it may be that theresin matrix itself is alkylated thereby detracting from catalyticactivity. One attempt was made to prepare a heterogeneous catalyst fromthe phenolic resin using 2,6-di-tert-butylphenol but this attempt wasnot successful. The catalyst prepared from phenolic resin,triethylaluminum, and 2,4-di-tert-butylphenol were active but somewhatslower and less selective for alkylation.

According to the process of the invention, the aluminum compound may beadded to the resin for reaction therewith over a broad range oftemperatures so long as the attachment of the aluminum to the resinwithout destruction of the resin is accomplished. A suitable range oftemperatures for this addition is -20° C. to about 75° C. preferably-20° C. to about 35° C. Conveniently, the aluminum or aluminum compoundis added at about room temperature. This is especially facile foraluminum alkyl compounds which readily react with the resins to attachaluminum thereto.

The phenoxide-donating phenol may be added to the aluminum-bearing resinover a broad range of temperatures as well so long as formation of theresin-bonded aluminum phenoxide heterogeneous catalyst is accomplished.For formulation of the heterogeneous "ortho" catalyst, theortho-alkylphenol is preferably added at the minimum temperaturepossible while still forming catalyst. This minimizes transalkylation ofthe ortho alkyl group (e.g., tert-butyl). The time of exposure of thephenol to the aluminum-bearing resin may vary depending upon the amountof phenoxide desired and the temperature used. A suitable range forformation of the phenoxide is about -10° C. to 50° C.

If the reactive aluminum compound used to make the heterogeneouscatalyst was an aluminum phenoxide, e.g. aluminumtri-(ortho-tert-butylphenoxide), the resulting catalyst will bephenoxide substituted and a donor phenol will not be needed.

The addition of the reac.tive aluminum compound and thephenoxide-donating phenol may be accomplished at atmospheric pressurealthough subatmospheric and superatmospheric pressure may also be used.Conveniently, room temperature and pressure conditions are used forformation of the catalyst with aluminum alkyls. Preferably it isconducted under an inert atmosphere, e.g. nitrogen.

The alkylation reaction of the invention may be carried out over a broadrange of temperatures depending upon the heterogeneous catalyst used,the phenol to be alkylated, and the olefin used for alkylation. Thetemperature should be high enough to accomplish the alkylation of thephenol at a reasonable rate and low enough not to destroy the formedproduct, catalyst, or reactants prior to formation of the desiredproducts. A suitable range of temperatures for the alkylation proceduresin general is about -20° C. to 150° C., more preferably -20° C. to 120°C. For the embodiment using the heterogeneous ortho catalyst of theinvention, a suitable range of temperatures is about -20° C. to 50° C.,preferably -10° C. to 30° C.

A broad range of pressures is usable with the heterogeneously catalyzedprocess of the invention. The pressure should be high enough to provideadequate amounts of olefin to the phenol and catalyst mixture so as toaccomplish alkylation but not so high as to interfere with obtaining thedesired alkylation product or otherwise interfere with the reaction suchas by degradation of reactants or product. Normally, the alkylationprocess is carried out in excess of 100 psig. A suitable range is20-5,000 psig and a preferred range is 20-1,000 psig olefin pressure.When using the ortho-catalyst even lower pressures are possible dow toatmospheric.

The heterogeneous catalyst should be provided in such an amount thatadequate aluminum phenoxide reaction sites are available to alkylate thephenol with the olefin. A suitable range of catalyst amount is fromabout 1 weight part to about 10 weight parts catalyst to 100 weightparts of phenol to be alkylated. Advantageously, an autoclave or othersimilar pressure vessel is sealed and used for the alkylation reaction.Conveniently, 20% excess olefin is fed normally at room temperaturewhile the reaction mixture is constantly agitated. Thereafter, thetemperature inside the reaction vessel may be controlled at the desiredlevel.

The following non-limiting examples will illustrate the embodiments ofthis invention.

EXAMPLE 1

A 100 gram portion of fresh wet Rohm & Haas Duolite® S-761 solidpolymeric ion exchange resin was dried under vacuum at about 80° C.until substantially all of the absorbed water had been removed. Thisresulted in about 50 grams dry resin. The resin was then slurried in 200ml. dry toluene under a nitrogen atmosphere. A stoichiometric excess(about 20-25 ml.) of triethylaluminum (TEA) was slowly added to theslurry and was allowed to react until no further ethane evolution wasobserved. The resin (now about 59 grams) was then subjected to five(50-200 ml.) washes with dry toluene to remove all of the unreacted TEA.This assured the presence of only heterogeneous catalyst. Liquidortho-tert-butylphenol, 300 grams, was then slowly added to theresin/toluene mixture at room temperature (26° C.) and allowed to reactuntil ethane evolution ceased. The stoichiometric amount of phenolneeded can be determined from the amount of aluminum taken up on theresin and the single or double functionality of the aluminum. The weightratio of ortho-tert-butylphenol to resin was about 6:1. Theortho-tert-butylphenol/catalyst mixture was charged to an autoclave andsealed. Twenty percent excess of the amount required to make2,6-di-tert-butylphenol of isobutylene (about 125 grams) was fed at roomtemperature (27°-32° C.) with constant agitation of the reactionmixture. Initial reaction pressure was 60 psig, partially (about 15psig) due to the nitrogen blanket over the mixture prior to isobutylenefeed. The reaction vessel temperature was controlled at about 32° C.throughout the reaction. After 1 hour and 45 minutes the reaction masscontained 91% 2,6-di-tert-butylphenol. The heterogeneous catalyst wasreadily separated by decant. When a portion of the catalyst remainssuspended as small particles (due to resin bead breakage from agitationor other breakdown of the resin) additional catalyst material can bereadily recovered by simple filtration. Although the melting point ofproduct 2,6-di-tert-butylphenol is 36° C., the product mixture remainsliquid since small portions of reactant and by-product phenols stronglydepress the melting point below most ambient temperatures. Thus only thecatalyst falls out of the reaction mixture. The liquid of the reactionmass was decanted and subsequent reactions were carried out using thesame solid heterogeneous catalyst. The reaction rates decreased witheach successive cycle but 4 such cycles had reasonable rates to achievesignificant amounts of 2,6-di-tert-butylphenol before catalystregeneration was necessary.

Example 1 is represented in the Table below as Run 15.

EXAMPLE 2

Rohm & Haas XAD-8 solid polymeric resin, 100 grams, having an esterfunctionality was dried under vacuum at 80° C. until substantially allabsorbed water had been removed leaving about 90 grams dry resin. Theresin was slurried in 200 ml. dry toluene under a nitrogen atmosphereand excess (20-25 ml.) TEA was slowly added to the slurry at roomtemperature. No ethane evolution was observed. The resin was then washedfive times with 200 ml. portions dry toluene to remove any excessunreacted TEA. Ortho-tert-butylphenol, 300 grams, was then slowly addedto the resin/toluene mixture and allowed to react until ethane evolutionceased. The weight ratio of ortho-tert-butylphenol to catalyst was againabout 7:1. The ortho-tert-butylphenol/catalyst mixture was charged to apressure reactor vessel and sealed. Twenty percent excess isobutylene(145 grams) was fed at room temperature over 42 minutes with constantagitation. The reaction temperature was controlled at about 14°-16° C.throughout the entire reaction. Initial reaction pressure was about35-40 psig and a maximum pressure of 57 psig was reached. The finalcomposition contained about 76% 2,6-di-tert-butylphenol. Similar runswith the same materials and under the same conditions resulted in yieldsof about 87-88% and the time for the runs ranged from about 3 hours, 20minutes to 4 hours, 10 minutes. This example and the similar runs arerepresented in the Table below as Runs 30-32.

A series of experiments was carried out to demonstrate the applicabilityof the heterogeneous catalyst of the invention. The materials, operatingconditions, and results of those experiments demonstrating the use ofthe heterogeneous alkylation catalyst of the invention are summarized inthe Table below. In each case, the resin was reacted first withtriethylaluminum, the most readily available and facile aluminum alkyl,and then with ortho-tert-butylphenol. Isobutylene was the reactantolefin in each case. In some cases freshly prepared catalyst was usedwhereas in other cases the catalyst was recycled for a subsequentexperiment as indicated.

                                      TABLE                                       __________________________________________________________________________                     TIME       PRODUCT ANALYSIS*                                 RUN NO.                                                                             RESIN TYPE (HRS.)                                                                             TEMP. °C.                                                                    OTBP                                                                              2,6-DTBP                                                                            2,4-DTDP                                                                            2,4,6-                                                                            DIMER                                                                              2TBP--BE                                                                            PTBP               __________________________________________________________________________     1    Thiol      17.00                                                                              29-51 7.0 88.0  --    4.2 --   0.8   --                  2    Thiol (recycle)                                                                          18.00                                                                              28-32 97.8                                                                              1.3   --    --  --   0.9   --                  3    Phenolic   9.00 28-93 58.6                                                                              17.6  17.8  3.0 1.0  1.3   --                  4    Mixed Amine                                                                              6.50 28-71 95.7                                                                              2.3   0.5   0.2 --   0.9   0.5                 5    Thiol (fresh)                                                                            8.17 27-37 16.6                                                                              74.6  1.1   6.3 0.4  0.4   0.6                 6    Thiol (recycle)                                                                          23.00                                                                              23-38 33.4                                                                              61.1  0.9   3.4 0.3  0.7   0.3                 7    Phenolic (fresh)                                                                         2.33 19-39 3.8 84.5  0.3   9.5 1.0  0.2   0.3                 8    Phenolic (recycle A)                                                                     20.50                                                                              25-44 1.9 90.0  0.2   6.8 0.3  0.5   0.2                 9    Phenolic (recycle B)                                                                     22.50                                                                              24-42 7.9 85.7  --    5.8 --   0.7   --                 10    Phenolic (recycle C)                                                                     48.00                                                                              22-36 5.4 86.5  0.4   6.3 0.4  0.7   0.3                11    Phenolic (fresh)                                                                         14.00                                                                              27-43 0.9 89.9  --    8.2 0.5  0.6   --                 12    Phenolic (recycle A)                                                                     23.25                                                                              27-46 15.3                                                                              77.7  0.6   5.0 0.4  0.7   0.2                13    Phenolic (recycle B)                                                                     74.00                                                                              22-41 64.3                                                                              28.5  0.6   1.4 0.1  0.9   0.1                14    Phenolic (recycle C)                                                                     0.33 37-39 96.0                                                                              3.0   0.1   0.1 --   0.8   --                 15    Phenolic (fresh)                                                                         1.30 19-33 1.6 90.8  --    6.8 0.3  0.5   0.5                16    Phenolic (recycle A)                                                                     23.42                                                                              23-38 22.5                                                                              63.5  7.1   4.2 0.2  --    1.8                17    Phenolic (recycle B)                                                                     4.92 24-29 78.4                                                                              19.5  0.4   1.5 --   0.2   --                 18    Phenolic (fresh)                                                                         43.00                                                                              -9 +27                                                                              2.3 90.1  --    7.6 --   --    --                 19    Phenolic (recycle)                                                                       28.25                                                                              13-33 86.5                                                                              11.8  .2    1.0  .1  0.2   0.1                20    Phenolic   ABORTED DUE TO WET RESIN                                     21    Phenolic (fresh)                                                                         3.08 26-35 5.0 84.3  0.3   9.1 0.6  0.2    0.2               22    Phenolic (recycle A)                                                                     25.90                                                                              24-44 14.4                                                                              75.6  0.9   8.0 0.6  0.2    0.2               23    Phenolic (recycle B)                                                                     NO REACTION OBSERVED                                         24     Acrylic Ester (fresh)                                                                   2.20 29-31 10.7                                                                              75.6  2.7   9.5 0.6  --    --                 25    Acrylic Ester                                                                            1.60 28-32 1.7 87.3  0.2   10.1                                                                              0.4  --    --                       (recycle A)                                                             26    Acrylic Ester                                                                            3.90 27-33 2.2 89.4  --    7.6 0.4  --    --                       (recycle B)                                                             27    Acrylic Ester                                                                            5.25 24-33 8.1 85.1  0.3   5.6 0.5  --    --                       (recycle C)                                                             28    Acrylic Ester                                                                            7.00 28-32 22.2                                                                              72.7  0.6   3.7 0.3  --    --                       (recycle D)                                                             29    Acrylic Ester                                                                            7.60 33-43 57.7                                                                              48.7  1.3   2.1 0.3  --    --                       (recycle E)                                                             30    Acrylic Ester                                                                            3.67 14-16 15.6                                                                              75.8  1.4   6.4 0.3  0.2   --                       (fresh)                                                                 31    Acrylic Ester                                                                            3.75 13-16 4.8 88.0  0.2   5.9 0.3  0.2   0.3                      (recycle A)                                                             32    Acrylic Ester                                                                            4.17 15-16 8.0 87.1  0.2   3.9 0.3  0.3   0.2                      (recycle B)                                                             33    Acrylic Ester                                                                            23.37                                                                              14-17 35.3                                                                              60.1  0.8   2.1 0.2  0.4   0.2                      (recycle C)                                                             34    Carboxyllic Acid                                                                         NO REACTION OBSERVED                                         35    Phenolic   NO REACTION OBSERVED                                         36    Phenolic   1.75 25-38 1.0 90.9  0.1   6.9 0.5  0.3   0.2                37    Phenolic (recycle)                                                                       3.58 23-34 4.6 87.6  0.3   6.4 0.5  0.4   0.2                38    Phenolic   5.37 32    6.9 83.5  0.5   6.3 0.4  0.3   0.1                __________________________________________________________________________     Product analysis is by weight percent exclusive of light ends. OTBP           orthotert-butylphenol; 2,6DTBP is 2,6di-tert-butylphenol; 2,4DTBP is          2,4di-tert-butylphenol; 2,4,6 is 2,4,6tri-tert-butylphenol; DIMER is          1,1,3,3tertramethyl-butylphenol; PTBP is paratert-butylphenol; 2TBP--BE i     2tert-butylphenyl butyl ether.                                           

The relatively slow reaction rates in experiments 1-7 were attributed topoor catalyst preparation. In Run No. 7 the thermocouple wasaccidentally left out of the thermal well resulting in somewhat highertemperature during the first portion of the alkylation. This did notseem to seriously affect the alkylation. In Run No. 11 theortho-tert-butylphenol was first dried with a molecular sieve to lowerthe water level and increase the ortho directing effect of theheterogeneous ortho catalyst. The drying reduced the water level of theOTBP from 0.05% by weight to 0.013% by weight. In Run No. 12 anadditional portion of isobutylene was charged after 20 hours of reactionand warmed somewhat for the continued reaction. The recycled phenolicresin heterogeneous catalyst of Run No. 14 was washed with 350 ml oftoluene at 150° F. for 20 to 30 minutes but this did not seem to improveits activity.

In Runs 15-17 toluene was used as a diluent to cleanse the resin. In Run16 the dipleg became plugged and the reaction vessel was opened toobtain the sample but some isobutylene was lost. The isobutylene wasrecharged but at too low a level thereby decreasing the production ofthe desired 2,6-di-tert-butylphenol. Runs 15-17 were diluted with 24% byweight toluene whereas Run 18 was diluted with 75 ml of toluene in areaction which contained 300 grams ortho-tert-butylphenol. In Run 18 thetemperature was only briefly at 27° C. and primarily at about 16° C. InRun No. 19 there was no apparent reaction for reasons unknown. Run No.20 was aborted because the resin was not well dried prior to preparationof the heterogeneous catalyst.

Run 21 was diluted with methylene chloride and some additionalisobutylene was added after about 2 hours and 20 minutes. This assuredcomplete reaction of the olefin with the ortho-tert-butylphenol. Run 22was carried out using 50 ml methylene chloride diluent and with a 30%stoichiometric excess of isobutylene.

The prepared heterogeneous catalyst of Run 23 was refluxed in methylenechloride for 1 and 1/2 hours before charging and the reaction mixturedid not react after 19 hours. In Run No. 28 the reactor was vented afterdiscovering that nitrogen rather than isobutylene was being charged.Thereafter, isobutylene was charged and the reaction proceeded as usual.

In Runs 24-29, it was calculated that approximately 4.55 grams ofaluminum were reacted onto the resin and remained there after toluenewashes.

In Run No. 30 the isobutylene feed was completed after 48 minutes.Aluminum analysis of the decanted liquid, centrifuged liquid, and solidslayer revealed that about 59.3% of the aluminum charged to the resin waslost after the reaction. In Run No. 31 the isobutylene feed wascompleted in about 5 minutes and only about 11.2% of the aluminumcharged to the resin had been lost after the reaction. Similarly, in Run32 only about 3.1% was lost and in Run 33 about 6.8% was lost.

In Run No. 24 in the Table, the product solution was decanted and foundto contain 0.60 weight percent aluminum. The decant was filtered leaving0.45 weight percent aluminum. The filtered 0.15 weight percent aluminum(in the form of aluminum compounds and resin-aluminum catalystmaterials) was put back into the reactor for subsequent runs. In thenext run, a recycle, the amount of aluminum lost was 0.09 weight percent(after filtration) while the catalyst activity remained excellent. Inthe next four recycle runs the catalyst activity remained excellent togood and there was no loss of aluminum in any of the four runs. Theresin used was Rohm & Haas XAD-8 acrylic ester resin.

Similarly in Runs No. 30 through No. 33 in the Table, the total loss ofaluminum was 80.4 percent of the aluminum reacted onto the catalystbefore Run No. 30. Yet the reactivity remained high as seen in the Table(75.8% to 88.0% to 87.1% to 60.1% product 2,6-). Compare the loss offour quantities of aluminum loss for four successive homogeneouscatalyst runs. Thus for this sequence of reactions alone the aluminumloss is only about one-fifth that lost in homogeneous runs--and thecatalyst still has good activity.

The savings in aluminum is more than the simple cost of aluminum alone.The savings in reduced disposal cost is more significant than the costof the metal.

In the homogeneously catalyzed process, the aluminum is acidified withsulfuric acid to make aluminum sulfate which is soluble in the acidphase. The acid phase with aluminum sulfate is cut from the mixture andtreated with caustic to form aluminum hydroxide. This greatly increasesthe weight of the waste material but allows disposal thereof. Thisneutralized solution is mechanically dewatered somewhat and sent tolandfill where it must be closely monitored. The acid/base treatment ofthe homogeneous catalyst prevents loss of product which is somewhatsoluble in basic aqueous solutions.

Thus a significant decrease in the loss of aluminum per batch run (or ina fixed bed) represents a great savings in disposal handling and cost.

In Runs 34 and 35 no reaction was observed and this was attributed to abad resin batch. In Run 36 a fresh batch of resin was used and thehighest aluminum absorption rate of the series was achieved with only 5%loss of aluminum from the resin after the reaction. The mole ratio ofortho-tert-butylphenol to dissolved aluminum in Runs 36-38 was 182, 282,and 635 respectively. Only 2.9% of the aluminum was lost in Run 37 andonly 1.4% was lost in Run 38. It should be noted that Runs 36-38 were aseries of runs using the same catalyst (recycled to Runs 37 and 38).Thus, the total loss of aluminum from these three runs was only 9.3%.This should be compared with the massive loss of phenol-bearing aluminumwhich must be disposed of as a waste stream in a homogeneously catalyzedprocess.

In another experiment not listed above, phenol and isobutylene werereacted in the presence of a heterogeneous catalyst formed from Rohm &Haas Duolite® S-761 phenolformaldehyde resin and phenol (C₆ H₅ OH). Theyield at about 95° C was about 9.0% 2,6-di-tert-butylphenol.

It should be apparent to the skilled artisan that the invention may bevaried considerably in its practice without departing from its lawfulscope and true spirit as defined by the appended claims.

We claim:
 1. A resin-bonded aluminum phenoxide catalyst containing thestructure ##STR5## wherein R is tert-alkyl, x is 1 or 2, y is 1 or 2 andx+y=3 and the Resin is the residue of a solid polymeric resin.
 2. Thecatalyst of claim 1 wherein R is tert-butyl.
 3. The catalyst of claim 2wherein said resin is a phenol-formaldehyde condensation resin.
 4. Thecatalyst of claim 2 wherein said resin is a cross-linked acrylicpolyester resin.
 5. The catalyst of claim 1 wherein said resin containsin its polymeric structure functional groups having a highlyelectronegative atom with a donateable hydrogen atom or otherelectropositive leavinq group which facilitates reaction of the resinwith an aluminum compound.
 6. The catalyst of claim 1 wherein said resinis a phenol-formaldehyde condensation resin.
 7. The catalyst of claim 1wherein said resin is a cross-linked acrylic polyester resin.
 8. Aprocess for preparing a resinous catalyst useful in the alkylation ofphenols, said process comprising reacting a reactive aluminum compoundwith a solid polymeric resin to attach aluminum to said resin andthereafter reacting a phenol with the aluminum attached to said resin toform a resin-bonded aluminum phenoxide catalyst.
 9. The process of claim8 wherein said aluminum compound is an aluminum alkyl.
 10. The processof claim 9 wherein said aluminum alkyl is triethylaluminum.
 11. Theprocess of claim 8 wherein said resin is a phenol-formaldehydecondensation resin.
 12. The process of claim 8 wherein said resin is across-linked acrylic polyester resin.
 13. The process of claim 8 whereinsaid phenol is an ortho-alkylphenol.
 14. The process of claim 13 whereinsaid ortho-alkylphenol is ortho-tert-butylphenol.